SHANGHAI, CHINA—The cartoon that appeared last week on the Web site of the Chinese state news agency Xinhua was no laughing matter. It depicted a scientist wearing a tie emblazoned with the American flag, staring through a microscope while dropping unnaturally colored kernels of rice into a Chinese child's mouth. It ran with a story headlined, "More shameful than the experiment are the lies."

The illustration is part of a media firestorm now engulfing a 4-year-old study in which Chinese schoolchildren were given golden rice, a genetically modified form of rice designed to boost vitamin A levels. The results of that study, published online early in August, drew little attention until the activist group Greenpeace China on 29 August claimed the trial shouldn't have gone forward and called it a "scandal of international proportions."

Defenders of the trial, including the U.S. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), which partly funded the research, have countered that the scientists conducting the research got all the necessary legal and ethical permissions. Greenpeace's actions are "callous and cynical," says Adrian Dubock, manager of the Golden Rice Project in Dornach, Switzerland, who was not involved in the study but has followed it closely.

Newspaper columnists in China have nonetheless responded by accusing the main authors, both at Tufts University in Boston, of using the kids as "guinea pigs"; some stories likened the study to Japanese bio-warfare experiments on Chinese prisoners in World War II.

The furor has prompted several Chinese scientists listed as co-authors on the published paper to distance themselves from the work, and one co-author was suspended just this week by the China Center for Disease Control and Prevention (Chinese CDC) for "inconsistencies" in what he told the agency about the study.

Golden rice was created in the late 1990s as an attempt to help people worldwide suffering from vitamin A deficiency, which is estimated to cause blindness in more than a quarter of a million children annually. The rice variety produces β-carotene, a precursor to vitamin A not naturally present in rice. Greenpeace has long attacked the project as a waste of money and a PR ploy by the industry.

The study in China sought to find out how efficiently β-carotene in golden rice is converted to vitamin A once it's ingested. According to the published study, which was conducted in 2008, the researchers fed 72 children either golden rice, spinach, or capsules with β-carotene in oil. They reported that golden rice was as good a vitamin source as the capsules, and better than spinach—a "fantastic result," Dubock says, because it means modest amounts of rice will provide benefits.

But Greenpeace China claimed in a press release that the study had violated a Chinese government "decision to abort plans for the trial." As evidence, the group cites a 2008 e-mail from an official in the Chinese agriculture ministry's GMO Biological Safety Administration Office.

In 2009, after the study was already done, NIDDK responded to another group's criticism by noting the work was approved by ethical panels at Tufts and the Chinese Academy of Preventive Medicine, that there were "many safeguards" to protect participants, and that the U.S. Department of State had cleared the trial after a review for "any potentially negative foreign policy implications."

In the wake of the uproar, the Chinese coauthors have denied involvement in the work. On 5 September, for example, the state-run People's Daily quoted Wang Yin of the Zhejiang Academy of Medical Sciences, the fourth author on the paper, as saying "I am unaware of that paper."

Yet the Chinese CDC confirmed that the Chinese researchers, including CDC's Yin Shi'an, collaborated with researchers at Tufts. The agency, however, stated that they only gave the school children spinach and capsules; the golden rice part was a Tufts project of which Yin had been unaware, a CDC statement suggested. Nonetheless, CDC suspended Yin for "inconsistencies" in his story.

Dubock says he has received information that the Chinese researchers had been "intimidated" by home visits from police. "Of course they knew" that golden rice was being tested, he says.

None of the Chinese scientists listed as co-authors could be reached for comment by Science. Tufts University said it is "deeply concerned" by Greenpeace China's allegation and is conducting a "thorough review." Pending the outcome, an interview with the paper's first author, Guangwen Tang, would be "not appropriate," a spokesperson says. (Tang is a Chinese-born researcher at a Tufts nutrition lab sponsored by the U.S. Department of Agriculture, the other funder of the study.) The paper's last author, renowned nutrition scientist Robert Russell, was also unavailable for comment due to family circumstances.